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Calculating the Volume of Wax Needed for a Candle Mold


filling votive molds

Filling votive molds

David Fisher
I know - when we were kids, we just threw some grocery store wax into a coffee can, melted it on the stove, and made some candles with string for wicks in milk cartons. While it may seem easiest to just melt some wax, add some color and fragrance, and pour it into your mold or containers, it's not the most efficient use of your ingredients. Wax, color and fragrance all cost money - and wasted wax equals wasted money.

I want you to always be able to enjoy your hobby as frugally as possible…so I've put together some formulas for you to be able to calculate just how much wax you need to fill a particular candle mold.

Calculating how much wax to use in a mold.
Warning - you're going to have to do some math here…but it's pretty easy.

First, determine what sort of mold you have:

  1. Rectangular or Square mold
  2. Cylindrical mold
  3. Odd, fluted or irregular shaped mold - including container candle jars
For a rectangular mold, the first thing to do is calculate how many cubic inches are in the mold. You do this by multiplying:

Height X width X depth

So, if you have a square mold that is 3" square by 4" high, the formula would be 4 X 3 X 3 = 36 cubic inches

Now, wax takes up about 2 cubic inches per ounce (or 28.35 grams) . So, divide the total cubic inches by 2 - and that gives you the total ounces of wax for your candle.

36 cubic inches / 2 = 18 ounces (510 grams) of wax

For a round pillar mold, the calculation is a bit more complicated. You have to calculate the cubic inches, but here the formula is: PI (3.14) X radius (half of the diameter/width of the candle mold) squared X height

So if you have a 3" round pillar mold that is 6" tall the formula would be PI (3.14) X 2.25 (half of 3" squared - 1.5 X 1.5 = 2.25) X 6 = 42.39 cubic inches

Divide the 42.39 by 2 (2 cubic inches per ounce of wax) and we get 21.20 ounces of wax for this candle.

Now, let's say you're math challenged…or have a mold like a taper, ornamental or votive mold that has a tapered or irregular shape - or pretty much any sort of container candle jar or making dixie cup votives. The secret weapon - water! First, weigh the empty mold. Then, fill the mold with water and weigh it again. Subtract the weight of the empty mold with the weight of the filled mold - essentially calculating the weight of the water in the mold. Multiply the weight of the mold by .86 to get the amount of wax needed.

For example, let's say you have a votive mold. Empty, it weighs 1.5 ounces. Filled with water, it weighs 4.5 ounces. That equals 3 ounces of water weight. Multiply 3 X .86 to get 2.58 ounces of wax.

Calculating the amount of wax needed for a candle that has embeds or chunks in it.
Chunk candles are very popular candle variations…but they can seem to present a bit of a challenge in calculating how much wax to melt. It's really not that hard.

First, calculate the total amount of wax you would use in this candle without the chunks or embeds. Weigh the chunks or embeds you are going to use in the candle. Subtract that weight from the amount of wax to use in the filler or overpour.

So, for example. You're making 6 chunk votive candles - that would normally hold 2 ounces of wax each. That's 12 ounces of wax you would normally use. You've already made your chunks and set your wick pins or wicks into the mold. Put the chunks into the molds like you want them first. Then pour out the chunks you've used and weigh them. Let's say that the chunks weigh out at 7 ounces. So that means you'll need 5 ounces of over pour wax to fill these chunk votives.

7 ounces of chunks + 5 ounces of over pour = 12 ounces of total wax

So...using these formulas, you should be able to minimize the wax and other ingredient waste - and know just how much wax you need for each and every mold you have.

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